1. Field of the Invention
The present invention relates to a needle assembly having safety elements for safe and convenient handling. More particularly, the present invention relates to a needle assembly having a double-ended needle for collecting or delivering fluid samples from or into a patient and which includes a retracting assembly for retraction of the needle.
2. Description of Related Art
Disposable medical devices having piercing elements are typically used for administering a medication or withdrawing a fluid, such as blood collecting needles, fluid handling needles and assemblies thereof. Current medical practice requires that the fluid containers and needle assemblies used in such systems be inexpensive and readily disposable. Consequently, existing blood collection systems, for example, typically employ some form of durable, reusable holder on which detachable and disposable needles and fluid collection tubes may be mounted. A blood collection system of this nature can be assembled prior to use and then disassembled after use.
A popular design configuration of previously available blood collection systems includes a double-ended needle assembly, an evacuated collection tube, and a holder for maintaining the needle assembly and the collection tube in fixed relation. The double-ended needle assembly, which is also referred to as a cannula, has a bore extending therethrough and a hub near a central region thereof The evacuated fluid collection tube includes a puncturable stopper at one end thereof. In this type of blood collection system, the holder typically has a housing at one end thereof for receiving the needle assembly. Likewise, the holder also has a hollow body with an opening at an opposite end thereof for receiving the collection tube. The needle assembly is rigidly received within the housing of the holder such that a first end of the needle extends forwardly of the holder for puncturing a vein of a patient. The opposite, second end of the needle extends into the hollow body of the holder. Upon assembly of the blood collection system, the needle assembly is inserted into the housing and the collection tube is inserted through the open end of the hollow body until the second end of the needle pierces the puncturable stopper of the collection tube, thereby allowing fluid communication between the interior of the collection tube and the bore which extends through the needle assembly. To draw a blood specimen from a patient using one of these blood collection systems, the evacuated collection tube is partially inserted into one end of the holder, the first end of the needle is inserted into a patient's vein, and the collection tube is fully inserted into the holder such that blood will be drawn through the bore of the needle assembly and into the fluid collection tube. After drawing the specimen, the collection tube is removed so that the blood contained therein can be analyzed and the needle assembly is detached for disposal.
In addition to being capable of accommodating blood collection tubes, the holders of some fluid transfer systems are compatible with fluid containers having a fluid to be injected into a patient. Thus, such holders can be used to inject fluid into, as well as draw blood specimens from, a patient.
In order to reduce the risk of incurring an accidental needle-stick wound, protection of the used needle tip becomes important. With concern about infection and transmission of diseases, methods and devices to enclose the used disposable needle have become very important and in great demand. Many arrangements have been designed for protecting used needle tips involving retracting the needle within a housing. For example, U.S. Pat. No. 5,810,775 to Shaw discloses a collection assembly which provides for retraction of the intravenous needle at the patient end of the assembly, and further discloses a hinged cap at the open end of the housing of the holder. After drawing a specimen into a collection tube, the collection tube is removed, and the hinged cap is closed over the opening of the holder, thereby activating the needle retraction and blocking access to the second end of the needle at the non-patient end. Activation of the hinged cap and the retraction mechanism requires substantial manipulation by the user and cannot be conveniently accomplished with a single hand, as is ideal for typical phlebotomy practice.
U.S. Pat. No. 4,846,808 to Haber et al. discloses a safety syringe including a needle, which can be manually retracted by sliding an inner needle carrier within an outer housing. The needle carrier includes a portion which can be pivoted to rotate and bend the needle to a canted and bent position toward the outside sleeve. Such an assembly requires multiple movements of the needle carrier by the operator to retract and to pivot and bend the needle, and does not provide effective protection at the non-patient tip of the needle within the housing.
Accordingly, a need exists for a needle assembly which provides effective protection from both ends of a double-ended needle with simple and efficient retraction of the needle, and which is simple to manufacture and easy to operate.